Viscous liquid dispensers are well known in the art for dispensing any manner of viscous liquid, for example lotions, soap, and the like. The conventional dispensers utilize a wide variety of pumping mechanisms which allow a user to depress or manipulate a pump actuator in order to dispense liquid from the dispenser. Exemplary devices are shown, for example, in U.S. Pat. Nos. 5,810,203; 5,379,919; 5,184,760; and 4,174,056.
Conventional dispensers and pump mechanisms are often configured with locking mechanisms to reduce leakage during shipment or storage. However, locking mechanisms often fail to fully stop leakage, especially in those pumps having a pump mechanism at or below the level of the liquid in the dispenser.
Pump mechanisms with check valves are also known. However, check valves are often designed to work in conjunction with pressure developed through activation of the pump. When the pump is in locked position, there is no pressure being developed to activate the check valve. Also, check valves may improperly seat and allow small leaks that would be insignificant during dispensing, but become significant during extended periods of shipment or storage.
Therefore, there remains a need in the art for a dispenser and dosing pump mechanism having improved capability to prevent leakage during shipment or storage thereof.